Today Ethernet is the standardized “de facto” interface and layer 2 connecting solution in Home, SOHO and Enterprise networks. The main advantage of Ethernet is its plug and play property, which makes it possible to connect any terminal to the Home/Enterprise network without any installation/configuration. Further important property of Ethernet is transparency, i.e., it provides simultaneous services (e.g. intranet/internet connectivity), protocol stacks (e.g. TCP/IP, UDP/IP) as well as IP addressing transparency.
Ethernet is also in the focus of the standardization activities in IEEE, resulting that today Ethernet is much more than a simple data-link layer protocol. The continuous standardization of Ethernet control and management plane makes possible that Ethernet can play important role outside the Local Area Network (LAN) environment. A clear example for this tendency is the increasing penetration of layer 2 VPN solutions, which may be more effective than the other alternatives from the viewpoint of both OPEX and CAPEX.
In summary, Ethernet is becoming the major connectivity protocol for SOHO/Enterprise networks, and it is becoming “well-known” for home users. The current Ethernet hype results that the number of future Ethernet-based applications will increase continuously.
On the other hand, it is clearly seen that the role of mobility and mobile networks have also very important role in communication. Many use cases are possible when a connectivity between the moving user and the Home/Enterprise network would be desirable (just an example is when the user wants to reach the hard disk of his Home PC from where the user wants to download e.g., some mp3 music files to his laptop, while he is travelling on the train using mobile Internet access via a 3G data card).
The evolution of mobile systems culminating in Long Term Evolution/System Architecture Evolution (LTE/SAE) systems will make it possible for the mobile operators to offer true broadband data services for the subscribers. Moreover, there is also a possibility to offer fixed broadband services using 3GPP technology. This is possible via the 3G Fix Wireless Terminal (FWT). The FWT is a similar device as the broadband home router in xDSL access: it provides Internet connection to multiple computers on an LAN via NATing and firewall service. The internal interface is an Ethernet switch. The difference to Digital Subscriber Line (DSL) broadband routers is that the WAN interface of the FWT is a cellular (e.g. HSPA or LTE) interface connected to a mobile network.
From the above it is obvious that use cases of mobile Intranet access, similar to that described above will become frequent and will demand appropriate solutions for home or corporate Intranet access from the mobile operator.
Today, of course, the Layer 3 connectivity between a moving User Equipment (UE) and Home/Enterprise network via Mobile network is possible, but transparent Ethernet (layer 2) connectivity has some major advantages and provides much simpler realization of connectivity, namely:                No need for installation of any new client software in the terminal (e.g. PC/laptop), all required functionality can be handled by the Mobile Terminal on the moving user side, and the Customer Premises Equipment (CPE) on the fix network side. Since the connectivity between the moving terminal and the Home/Enterprise network is established on Ethernet level, the moving user is the part of Home/Enterprise LAN        IP-addressing transparency: the user will get IP address from the Home/Enterprise Dynamic Host Configuration Protocol (DHCP) server, optionally from his fix operator. This means that the user will be in his/her Home/Enterprise subnet/VPN.        Since transparent layer 2 connectivity is established all Ethernet level information e.g. VLANs can be forwarded transparently.        
For layer 2 transparent access of Home/Enterprise network, two possible application scenarios are described below:                Mobile intranet scenario: In this case several mobile/branch offices are connected to the Head office using mobile network access. i.e., the connection is provided via a mobile terminal (mobile office) or a FWT (fixed office). This solution can be attractive for offices in order to provide layer 2 access to the head office.        Reaching Home/Content scenario: In this scenario a consumer is able to reach transparently his home content, as well as to control remotely different home equipments (heating system, web-cams, etc). Additionally, this scenario makes possible the reusing of home terminals (for example game consoles) in moving environment (e.g in a car) utilizing the plug and play feature of Ethernet.        
For providing Ethernet (layer 2) connection to a remote network, Layer 2 (L2) tunnelling or L2VPN technologies need to be used. The specific technology depends on the type of the network. For example, in IP network EtherIP or L2TPv3 may be used. In MPLS networks, Virtual Private LAN Service (VPLS) may be used. If the provider network is Ethernet, PBB (IEEE 802.1ah) may be used.
For tunnelling Ethernet frames the following alternatives exist:                EtherIP—RFC3378: This protocol is developed especially for transmission of Ethernet frames in an IP packet. The tunnelling header is two octets, which contains only a protocol version number, plus a reserved field for future use.        Layer 2 Tunnelling Protocol version 2 (L2TPv2)—see RFC2661.        Another currently standardised solution is to use L2TPv3 to transport Ethernet frames [RFC4719, “Transport of Ethernet Frames over Layer 2 Tunnelling Protocol Version 3 (L2TPv3)”] in an IP/UDP packet. In this case, PPP is not required, Ethernet can be transported directly on top of L2TPv3 decreasing the overhead.        VPLS (Virtual Private LAN Service): is a way to provide Ethernet based multipoint to multipoint communication (L2 VPN) over MPLS networks. This solution requires MPLS network between CSE and CSN, because the MPLS label contains the tunnel identification information.        PBB (Provider Backbone Bridges) is a solution currently under standardization (IEEE 802.1ah) to provide virtual private LAN service over an Ethernet transport. This could be used if there was an Ethernet network between the CSN and CSE.        
The present applicant has identified the following problems with Layer 3 tunnelling:
Solutions (L3VPNs and Mobile IP) already exist to establish layer-3 connection to the home network. Layer-3 corporate VNP connection is also possible in current mobile networks based on network-specific APNs and GGSN configuration.
While in certain cases layer 3 tunnelling may be appropriate to use (e.g., in case of larger enterprises having their own IT management), in some cases, e.g., SOHO environments, is the lack of layer 2 transparency, which causes that those future applications which require Ethernet on layer 2 (for example broadcast of L2 frames is needed) will not work when the Ethernet transparency is lacking between the moving user and Home/Enterprise network.
Furthermore, the Layer 3 tunnelling solution requires specific client software in the UE (the UE and the Home network is not the same IP subnet) in order to provide connectivity.
The following disclose methods and apparatus in this field: [RFC2661, Layer Two Tunnelling Protocol “L2TP”], [RFC 3378, EtherIP: Tunnelling Ethernet Frames in IP Datagrams], and [Internet Engineering Task Force (IETF) WG Layer 2 Virtual Private Networks (I2vpn), http://iettorg/html.charters/I2vpn-charter.html].
The present applicant has identified the following problems with existing possible Layer 2 tunnelling solutions:
Existing L2VPN solution, be it either over an IP, MPLS or Ethernet provider network, work on the scale of sites. This means that such solutions inter-connect customer LAN sites. As such they rely on static configuration which increases the management burden considerably.
If a L2 tunnel (e.g. EtherIP) was established end-to-end, then this would require modifications of the client user equipment. A further problem is that this kind of traffic appears in the (mobile) network as uncontrolled peer-to-peer traffic, to which the operator has no influence, and so this solution makes it difficult for the operator to introduce and deliver the home connection as a new service.
A problem with the direct Ethernet transmission over the air (e.g. using an Ethernet PDP context) is that it has many effects on 3GPP standardization, which practically means that this solution is not a real alternative.
It is desirable to address at least some of the above-mentioned issues concerning the existing approaches.
US 2004/0158705 discloses a method for providing a terminal with secure access into 15 a remote network, using an acceleration server residing in the wireless network to provide performance optimisation. U.S. Pat. No. 6,970,459 discloses a protocol description for mobile subscribers in a fixed network in a wholesale service.